"For operational or business reasons we have started to see enterprise information systems connected to the OT systems. We all know that enterprise information systems are vulnerable to viruses, to malware," Yan says in an interview with Information Security Media group.

"One of the typical approaches [to secure OT] is that we allow the IT and the OT systems to connect but at the same time the connection must be tightly controlled," he says.

Yan, professor of computer science and engineering at Nanyang Technological University in Singapore, is a well-known cybersecurity researcher and practitioner. He has collaborated extensively with law enforcement agencies, government regulators, telecommunication operators and financial institutions on cybersecurity issues.